1. Field of the Invention
The present invention relates to a quality improver for use in producing bread that can give bread having a good dough property upon baking and being excellent in shape after baking, feeling upon eating and taste and difficult to be aged, to a method for producing bread using the quality improver and to bread produced using the quality improver as well as to a seed dough that can be stored at low temperatures and commercially circulated.
2. Description of the Related Art
Various developments for improving the flavor and feeling upon eating of bread have hitherto been produced. In particular, plain bread is required of flavor of bread itself, shape of bread after baking, feeling upon eating, etc. so that it is necessary to commercially produce bread that has soft feeling upon eating, good flavor and good storage stability.
Plain bread is produced generally by mixing wheat flour and yeast, kneading them and then allowing to primary fermentation to occur, dividing and molding the primarily fermented bread dough (seed dough), subjecting the molded bread to heating in an oven (finishing fermentation) at 30.degree. C. and then baking.
As the production method for plain bread, there has been known a so-called straight method in which such a work as above is performed in a series of operations and primary fermentation is performed using a sugar-added seed dough at a temperature of about 27 to 30.degree. C. in a short time. According to the straight method, generally bread having good flavor can be obtained. However, the bread tends to be aged quickly and the storage stability of the bread is poor. Also, a so-called intermediate seed method (sponge and dough method) is widely practiced, in which a sugar-non-added seed dough for plain bread is subjected to primary fermentation at a lower temperature (e.g., about 24.degree. C.) and for a longer time than in the straight method to prepare a seed dough (intermediate seed, sponge dough) and then sugar is added to the intermediate seed, which is kneaded together with wheat flour and division as well as molding and subsequent operations are carried out. In the case of intermediate seed method, a bread dough extends well and bread having soft feeling upon eating and good storage stability can be obtained. However, it has the problem that long fermentation time results in the generation of acid odor due to excessive fermentation, which deteriorates the flavor of bread.
In the straight method or the intermediate seed method, the fermentation of seed dough must be carried out under precisely controlled temperature and time in order to obviate excessive fermentation or insufficient fermentation so that the fermentation operation takes much labor. Therefore, circulation of a seed dough has been keenly desired but the circulation has been difficult. That is, in the seed dough containing yeast, the fermentation is not stopped by cooling or at normal temperatures. Therefore, excessive fermentation tends to occur during circulation and bread produced by using such a seed dough has deteriorated flavor. In freezing storage, the fermentation products (budding yeast) suffer damages due to freezing so that use of a frozen seed dough fails to give bread with a sufficient volume and having a good flavor.
Under the circumstances, methods for improving the circulation of a seed dough have been proposed. For example, Japanese Patent Application Laid-open No. Hei 8-242756 discloses that adjustment of the amount of water in the fermentation seed preliminarily alcohol fermented to 5 to 40% with powder of cereals enables the seed dough to be circulated in a cold state or at a normal temperature, thereby eliminating the step of fermenting a seed dough in the bread producing line to produce bread in a short time and producing bread having a good flavor, a soft inner phase and a soft feeling upon eating as well as good storage stability. As a method for enabling a dough to be frozen storable and circulable, it has been proposed to select a combination of yeasts so that they have different active temperature characteristics (Japanese Patent Application Laid-open No. Hei 7-313142).
To improve the flavor, shape after baking and feeling upon eating of bread, various substances have conventionally been added to a bread dough. For example, there has been known a method for increasing the activity of yeast including adding sugars and further saccharifying enzymes, koji (Aspergillus), etc. to supply sugars yeast assimilates. To give a fragrance, it has been known to add sake lees, a lactic acid fermentation product, fruit, etc. When a seed dough is produced, there is a trend that various synthetic chemicals that are not useful to human body are added as a quality improver, for example, for giving a soft feeling upon eating. For example, an emulsifier, a bromate oxidizing agent, etc. are added together with yeast food. In particular, in the case of emulsifiers such as glycerides, synthetic chemical preparations are used frequently commercially in view of the fact that they are more readily available than natural products and they are homogeneous.
Such bread is staple food, which is taken frequently and hence it is undesirable to add chemical synthetic additives thoughtlessly. Heretofore, natural materials, in particular those that function as yeast food, emulsifiers, etc. upon the production of a seed dough have not been known. Accordingly, there has been a keen desire for the development of a natural material quality improver that can give rise to bread of a desired quality when replacing thereby the chemical synthetic additives currently used widely and that can be utilized in the production of bread on a commercial scale without decreasing productivity.